Fault:
When the unit is turned on no audio output from either line L&R or headphone sockets. Factory defaults were then applied and still the same. The OS was upgraded from version 3.4 to 3.5. Still no audio after upgrade. It's a later model with the upgraded digital board.
Investigation:
- LFO led flashes and responds to contol, sync with keyboard flicks LED when key pressed. All front panel controls are providing input to the digital section, ie. change on the display when adjusted. Midi output is all working. Midi In worked as it upgraded okay.
- Output at the mixer (tested at the insert jack) seem to be present. This output seemed to be okay with various oscillators and modulation sources applied except for envelope modulation. The tone follows the keyboard and glide works.
- Audio can be produced from most patches when you switch ON/EXTERNAL to on and then cycle the power. This audio is only in the left channel (in the right ear from headphones), master volume and headphone volume are working. Simply turning ON/EXTERNAL to on does not create any output, nor does any key press. Turning off the gate does seem to result in the envelope decay running, however then turning the gate back on does not re trigger the envelope. Keyboard gate signal can be seen on pin 5 of the accessory port. Filter envelope can be seen on pin 21 of the accessory port when no audio and it seems to trigger from the keyboard although ADSR does not seem to respond correctly. The volume envelope pin 9 of the accessory port stays at 0V regardless of the keypress or the ON/EXTERNAL switch state.
- With audio running as above, the volume envelope sustain level controls the audio level and it follows the decay rate setting when adjusted down but not when adjusted up, although it does come up. Release seems to work when gate is turned off. Also holding a key while turning off the gate, holds the note and then when the key is released it releases as expected. Attack cannot be checked as I cannot trigger the envelope from the keyboard. Just holding a key down when you power up does not produce any output.
- With audio running as above, switching HP/LP on will kill the audio, turning LP/LP back on restores the sound. When audio is present the filter controls seem to work and track the keyboard. Modulation sources work to the filter. The filter envelope also controls the filter, the AMOUNT and SUSTAIN change the sound and the sustain level seems to track the decay time when changing the sustain level down but not when changing the sustain level up, although it does come up. The filter sweeps on the gate release. Attack cannot be checked as I cannot trigger the envelope.
As I understand it there are two filters in the Voyager, so one side of the filter or the right VCA has failed, I suspect the filter, as changing to HP/LP kills the audio. Trigging for the envelope is also not working.
Questions:
- The service manual would be helpful, is it available?
- I am happly to dig further without a circuit, I can see all the variable controls are using LM13700's, the switchs are all the old CMOS 4016, 4051,4052 and 4053 types and there is a pair of CA3046's which I assume is the transistor arrays used in the filter ladders. The silk screen narrows the area slightly but a pointer to where on the board to start looking would be a big assist?
- Has anyone seen anything like this before?
Thanks in advance
Spav
